GLS Seminar: Dr. David Blowes, "Predicting, Preventing, and Remediating Acidic Drainage from Sulfide Bearing Mines and Mine Wastes"

Wednesday, September 20th, 2006 from 4:00 PM – 5:00 PM, 4069 Derring Hall

Refreshments will be served at 5:00 PM. The public is cordially invited.

Predicting, Preventing, and Remediating Acidic Drainage from Sulfide Bearing Mines and Mine Wastes

Dr. David Blowes, University of Waterloo, Geological Society of America Birdsall-Dreiss Lecturer

The generation of acid mine drainage and the accompanying release of high concentrations of dissolved metals plague mining districts throughout the world. Without adequate control, acidic, metal-laden drainage devastates river courses and contaminates aquifers. Acidic drainage results from the biologically mediated oxidation of sulfide minerals in mine workings and mine wastes, and the transport of the reaction products along groundwater and surface water flowpaths. Over the past two decades, our understanding of the complex interactions between hydrogeology, microbiology, geochemistry, and mineralogy has advanced significantly. At the same time, reactive transport models have evolved rapidly to a high level of sophistication, providing a framework for integrating these highly coupled processes. Combining reactive transport modeling with the results of detailed field and laboratory studies provides an unprecedented ability to predict the potential impacts of mining activities and mine-waste disposal facilities prior to closure. Our improved understanding of the causes of acidic drainage has led to the development of new approaches to mine-waste disposal, including the segregation and selective disposal of sulfide minerals in subaqueous repositories or in cemented paste backfill and codisposing sulfide wastes with organic carbon to prevent sulfide oxidation and to promote sulfate reduction and secondary sulfide precipitation. At sites where acidic drainage persists, new and often passive approaches for remediating contaminated surface water and groundwater are providing new opportunities to protect water resources. This presentation describes conceptual models of the hydrogeochemical evolution of mine wastes and illustrates these conceptual models with examples from minesites throughout the world. I will describe approaches that can be used to understand and model the predominant physical and biogeochemical processes that control the extent and duration of contaminant release and provide examples of new techniques that are being developed to protect water resources from future contamination and to restore groundwater and surface water quality.